1. Field of the Invention
The present invention relates to an input device used for operating an electrical apparatus, for example, an air conditioner mounted on a vehicle, and particularly to a haptic feedback input device giving a predetermined haptic force feedback to an operator which operates manually a knob in response to the rotational direction and rotational angle of the knob.
2. Description of the Related Art
A conventional haptic feedback input device includes, for example, a haptic feedback input device having a manually rotated and moved knob, an encoder which detects the rotational angle of the knob, a push button switch which detects movement, a motor which applies a torque to the knob, and a controller which controls the motor in response to a rotational angle detected by the encoder and outputs an operating signal in response to the rotational angle to a separate apparatus as an object to be operated by the knob.
In the haptic feedback input device constructed as above, the knob is manually rotated, for example, to output an operating signal that operates an onboard electrical apparatus. Here, the air volume adjustment and outlet switching of an onboard air conditioner, the adjustment of sound volume of a radio or a tuner of the an audio system, or the adjustment of sound volume or sound quality of an audio system are objects to be operated.
In this case, first, after the knob is rotated to select an onboard air conditioner, etc. as an object to be operated, the knob is depressed to fix an apparatus as the object to be operated. Next, in a case in which the air volume of the onboard air conditioner is adjusted, for example, when the knob is rotated in a direction that the air volume increases, a torque is applied to the knob from the motor in a direction opposite to the rotating direction of the knob. At this time, with an increase in the rotational angle of the knob in the direction that the air volume increases, the torque in the direction opposite to the rotating direction of the knob is set to increase. In other words, an operator can grasp that the operating member 12 has been rotated to some extent in a direction that the air volume increases, from the haptic force feedback accompanied with an increase in a resistance force applied from the knob.
In addition, as above-mentioned, besides obtaining the resistance feeling as the haptic force feedback, the haptic feedback input device includes, for example, a haptic feedback input device in which an accelerating feeling can be obtained as the haptic force feedback by applying a torque to the knob in the same direction as the rotating direction of the knob, or a haptic feedback input device in which a click feeling can be obtained by reversing the torque applied to the knob when the rotational angle of the knob exceeds a predetermined rotational angle.
As such conventional haptic feedback input devices, an input device of type in which a motor and a knob are directly connected to each other, and the knob and the motor are simultaneously moved is known. This type of directly connected haptic feedback input device has a disadvantage that a torque as the feedback force is not sufficient because the transmission ratio of the motor to the knob becomes 1 to 1.
Therefore, nowadays, in order to make up for the insufficient torque, an input device has already been developed in which the only knob fixing the motor is movably supported, a pulley and a belt are provided for reducing the rotational speed of a rotating shaft of the motor to transmit an increased torque to the knob, and the motor and the knob are connected to each other via the pulley and belt (for example, see U.S. Pat. No. 6,128,006).
The conventional input device will now be described with reference to FIG. 7. The input device has a housing 126, an actuator (a motor) 112 supported by the housing 126, a sensor (an encoder) 110, a knob 66 which is rotatably and swingably connected to a rotating shaft 140 of the actuator 112 via a pulley 132 and a belt 138, and a push button switch 150 which detects the movement of the knob 66 during its swing.
Next, the operation of the input device will be described. When the knob 66 is rotatably operated, the rotating shaft 140 of the actuator 112 is rotated via the pulley 132 firmly fixed to a shaft 134 and the belt 138, and thereby the rotational angle of the knob is detected by the sensor 110 connected to the actuator 112. Then, a controller (not shown) controls the actuator 112 in response to the rotational angle detected by the sensor 110, and then outputs an operating signal in response to the rotational angle of the knob 66 to a specific apparatus as an object to be operated by the knob 66.
At that time, the actuator 112 is controlled in response to a signal from the controller. In this case, the actuator 112 and the knob 66 are connected to each other with the belt 138 via the pulleys 136 and the 132, and the diameters of the pulleys 136 and 132 are varied to alter the transmission ratio of the actuator 112 and the knob 66. Therefore, the rotational speed of the rotating shaft 140 of the actuator 112 can be reduced to transmit an increased torque to the knob, thereby transmitting a sufficient torque from the actuator 12 to the knob 66.
Further, by depressing the knob 66 after the knob 66 has been rotated to select an apparatus, as an object to be operated, among various kinds of apparatuses, the knob 66 and the shaft 134 are swung, and thereby the shaft 134 depresses the push button switch 150 via a drive member 148 which is disposed in a lower portion of the shaft. Then, a signal detected by the depression of the push button switch 150 is sent to the controller to determine an apparatus as an object to be operated.
However, in the structure of the above-mentioned conventional haptic feedback input device, when the knob 66 is depressed to move the shaft 134, the relative positional relationship between the rotating shaft 140 of the actuator (motor) 112 and the shaft 134 of the knob 66 is altered. Therefore, there is a problem in that the torque of the actuator (motor) 112 cannot be transmitted to the knob 66 via a flexible power transmission member 66, such as the belt 138, however, a direct haptic force feedback cannot be given as compared to the directly connected haptic feedback input device.